Buggy code:
public class ZoneTransferIn { private static final int INITIALSOA = 0 ; private static final int FIRSTDATA = 1 ; private static final int IXFR_DELSOA = 2 ; private static final int IXFR_DEL = 3 ; private static final int IXFR_ADDSOA = 4 ; private static final int IXFR_ADD = 5 ; private static final int AXFR = 6 ; private static final int END = 7 ; private SimpleResolver res ; private Name zname ; private int qtype ; private long ixfr_serial ; private boolean want_fallback ; private Stream stream ; private int state ; private long end_serial ; private long current_serial ; private Record initialsoa ; private int rtype ; private List axfr ; private List ixfr ; public static class Delta { public long start ; public long end ; public List adds ; public List deletes ; private Delta ( ) { } } private ZoneTransferIn ( ) { } private ZoneTransferIn ( SimpleResolver sres , Name zone , int xfrtype , long serial , boolean fallback ) { } private static SimpleResolver newResolver ( String host , int port , TSIG key ) throws UnknownHostException { } public static ZoneTransferIn newAXFR ( Name zone , SimpleResolver res ) { } public static ZoneTransferIn newAXFR ( Name zone , String host , int port , TSIG key ) throws UnknownHostException { } public static ZoneTransferIn newAXFR ( Name zone , String host , TSIG key ) throws UnknownHostException { } public static ZoneTransferIn newIXFR ( Name zone , long serial , boolean fallback , SimpleResolver res ) { } public static ZoneTransferIn newIXFR ( Name zone , long serial , boolean fallback , String host , int port , TSIG key ) throws UnknownHostException { } public static ZoneTransferIn newIXFR ( Name zone , long serial , boolean fallback , String host , TSIG key ) throws UnknownHostException { } private void openConnection ( ) throws IOException { } private void sendQuery ( ) throws IOException { } private long getSOASerial ( Record rec ) { } private void logxfr ( String s ) { } private void fail ( String s ) throws ZoneTransferException { } private void fallback ( ) throws ZoneTransferException { } private void parseRR ( Record rec ) throws ZoneTransferException { } private void closeConnection ( ) { } private void doxfr ( ) throws IOException , ZoneTransferException { sendQuery ( ) ; while ( ( state ) != ( ZoneTransferIn . END ) ) { Message response ; Record [ ] answers ; response = stream . next ( ) ; if ( ( response . tsigState ) == ( Message . TSIG_FAILED ) ) { fail ( "TSIG<seq2seq4repair_space>failure" ) ; } answers = response . getSectionArray ( ANSWER ) ; if ( ( state ) == ( ZoneTransferIn . INITIALSOA ) ) { int rcode = response . getRcode ( ) ; if ( rcode != ( Rcode . NOERROR ) ) { <START_BUG> if ( ( ( qtype ) == ( Type . IXFR ) ) && ( rcode == ( Rcode . NOTIMPL ) ) ) { <END_BUG> fallback ( ) ; run ( ) ; return ; } fail ( Rcode . string ( rcode ) ) ; } Record question = response . getQuestion ( ) ; if ( ( question != null ) && ( ( question . getType ( ) ) != ( qtype ) ) ) { fail ( "invalid<seq2seq4repair_space>question<seq2seq4repair_space>section" ) ; } if ( ( ( answers . length ) == 0 ) && ( ( qtype ) == ( Type . IXFR ) ) ) { fallback ( ) ; run ( ) ; return ; } } for ( int i = 0 ; i < ( answers . length ) ; i ++ ) { parseRR ( answers [ i ] ) ; } if ( ( ( state ) == ( ZoneTransferIn . END ) ) && ( ( response . tsigState ) == ( Message . TSIG_INTERMEDIATE ) ) ) fail ( "last<seq2seq4repair_space>message<seq2seq4repair_space>must<seq2seq4repair_space>be<seq2seq4repair_space>signed" ) ; } } public List run ( ) throws IOException , ZoneTransferException { } public boolean isAXFR ( ) { } public List getAXFR ( ) { } public boolean isIXFR ( ) { } public List getIXFR ( ) { } public boolean isCurrent ( ) { } }

Fix:
if ( ( ( qtype ) == ( Type . IXFR ) ) && ( rcode == ( Rcode . NOTIMP ) ) ) {